Brake drum



Sept. 27, 1938. T CH SE 2,131,614

BRAKE DRUM Filed May 26, 1957 Patented Sept. 27, 1938 BRAKE DRUM TheronP. Chase, Detroit, Mich., assignor to General Motors Corporation,Detroit, Mich, a corporation of Delaware Application May 26, 1937,Serial No.144g98 Claims.

This invention relates to brakes and particularly to brakes for use onvehicles.

Specifically, the invention aims to provide an improved brake drum foruse with vehicle wheels. 5 The main object of the invention is so tomodify the conventional drum as to facilitate cooling when the drum issubjected to the heating effect of frictional engagement with the brakeshoes.

A secondary, but nevertheless important, object is the accomplishment ofthe main object by a construction which will be simple and which willinvolve but little expense over the cost of a drum without provision forcooling.

Other objects and advantages will be understood from the followingdescription.

In the drawing: Figure 1 is a view of the novel drum in elevation.

Figure 2 is a section on line 2-2 in Figure 1.

Figure 3 is a section on line 3--3 of Figure 1.

Figure 4 shows in transverse section a modification.

Referring to the several figures of the drawing, numeral 5 is ashoe-engaging annulus to which a closure disc I is secured. The disc Iis shown with holes 9 for the passage of fastening means for attachingthe drum to a vehicle wheel. Preferably, the disc is of sheet metal andhas axially directed parts II by which the annulus, preferably ofcast-iron, is secured to the disc in the act of casting. As shown in thedrawing, the cast annulus has a radial flange l3 and extending axiallyalong the outer face of the annulus there are cooling ribs l5, theseribs terminating at the flange.

At this point it may be said that such axial ribs are easily andinexpensively formed in the process of casting the drum. Taken bythemselves such axial ribs are less efilcient for cooling thancircumferential ribs for the reason that the direction of drum rotationis perpendicular to the ribs. Circumferential ribs are, however, farmore expensive to form, requiring either a large expensive core itformed when casting the drum or requiring a thick wall which is to besubsequently machined to form grooves and ribs.

This invention makes use of the inexpensive axial ribs and to produce acirculation of air between the ribs there is provided a shallow cup- 50shaped stamping H. The annular side wall IQ of this cup-shaped stampingoverlies the ribs l5 and stops somewhat short of the flange 13. The

base 2| of the stamping extends over and is holes 9. There are aplurality of depressed portions 25 in part 2|, these depressed portionsarranged in a circular series. These depressed portions only contactwiththe disc I and the disc and the cup are riveted as at 21 or otherwise 5secured together in these regions of contact.

When a vehicle with drums such as are described above is traveling, acurrent of air flows in the direction of the arrows entering between thebase 2| of the shallow cup and the disc I as at 23. The air passes overthe annulus 5 and between the ribs and escapes adjacent the flange I3.Such a drum is but a little more expensive to manufacture than a drumhaving no provision for cooling. There is no appreciable addill tionalexpense in casting the annulus with the axial ribs and the cost of thecup-shaped stamping is negligible. A drum so made is efliciently cooled.Such an expedient is of particular utility in vehicles now beingproduced where provision of high speed requires a provision for severebraking and where, too,'smaller wheels seriously restrict the size andbraking area of the brake drum annulus.

Figure 4 shows a slight modification. Brake drum 5 with its ribs l5remains unchanged. The stamping ll differs slightly from the stampingll. Instead of being attached rigidly thereto by rivets 21, it isresiliently secured thereto with provision for a slight circumferentialmovement relative to the drum. In place of each of the rivets 21 shownin Figure 1 there may be secured to the disc I a retaining bolt 3|. Thestamping I1 is provided with a plurality of openings to surround thesebolts, the opening affording a limited degree of clearance as shown at33. A coil spring 35 engages the depressed portion of the stamping I1and has for its outer abutment a member 31 secured in any preferred wayto the bolt 31. The resiliently restrained slight circumferentialmovement makes possible a frictional engagement between the wall of themember I1 and the ribs 15. This is intended to prevent brake drumsqueals.

I claim:

1. A brake drum having a braking annulus and an attaching disc securedthereto, said annulus having axial ribs, and a cup-shaped stampinghaving a base positioned to form a space between said base and disc andhaving an annular wall overlying said ribs whereby the space between thebase and the disc is in communication with the spaces between the ribsand the overlying annular wall.

2. A brake drum having a disc and a braking annulus, the latter ofcast-iron with axial ribs on its outer surface, said disc and annulusbeing secured together; and a stamped cup having a base secured to butin spaced relation from said disc and having an annular wall overlyingsaid ribs.

3. A brake drum having a braking annulus of cast-iron formed with aradial flange and a plurality of axially extending ribs on its outersurface, said ribs extending to said flange, an attaching closure membersecured to said annulus for securing said annulus to a wheel, a stampedcup having a base secured to but in spaced relatior. from said closuremember and also having an annular flange overlying said ribs andterminating a short distance from said flange.

4. A brake drum having a braking annulus and an attaching disc securedthereto, said annulus having axial ribs, and a cup-shaped stampinghaving a base secured to said disc and an annular wall overlying saidribs, the attachment of said stamping providing a limited relativecircumferential movement between said stamping and said drum.

5. A brake drum having a braking annulus and an attaching disc securedthereto, said annulus having axial ribs, and a cup-shaped stampinghaving a base secured to said disc and an annular wall overlying saidribs, the attachment of said stamping comprising a plurality of saidbolts carried by said disc, said stamping having enlarged openingssurrounding said bolts, and yielding means holding said stamping againstsaid disc.

THERON P. CHASE.

